Treatment planning of damaged teeth: to recover or to extract?

BACKGROUND: Planning the treatment of a compromised tooth is challenging but the choice should refer to evidence-based criteria. The literature proved that patient-related factors influence the treatment plan, but what happens when the patient is a dentist? Aim of the study was to observe whether the dentist goes for the same option suggested to a patient in a hypothetical scenario. METHODS: One hundred volunteers were interviewed singularly in a quiet ambient. Radiographs of 15 compromised teeth were shown and were identified as belonging to a hypothetical patient with non-contributory medical history asking for the best treatment. For each clinical case, the dentist could decide between: extraction (E), endorestorative recovery (R); referral to a specialist (S) to save the tooth. After a 15-minute wash-out, the same radiographs were shown again with the question: if this was your tooth, what would you do? The alternatives could be E or R. Statistical analysis was performed in order to evaluate the discordance between the choice taken for the patient and for the dentist's teeth. RESULTS: A constant increase in recovered teeth was observed in group D with the only exception of case 12. Concordance ranged from scarce to substantial, while symmetry showed that, when changing their mind, the dentists recovered their own teeth. CONCLUSIONS: The dentists were more conservative on their teeth: this shows the absence of a coherent decision-making pattern and stresses the need for an improvement in the formation of dental practitioners.

Comparison of marginal fit of Lava CAD/CAM crown-copings with two finish lines.

PURPOSE: Marginal fit is valued as one of the most important criteria for the clinical quality and success of all-ceramic crowns. The aim of this in vitro study was to investigate the marginal fit of Lava Zirconia crown-copings on chamfer and shoulder preparations. METHODS: Two acrylic model teeth were selected to simulate the clinical preparations: one molar was prepared with a chamfer finish line (C) and one premolar was prepared with a rounded shoulder finish line (RS). Each resin model was duplicated 10 times using silicon-based impression material and poured in type IV dental stone for the fabrication of working dies. A total of 20 copings were divided into two groups (n = 10 for each finish line). Fifty measuring locations were chosen randomly along the margin on the dies and the gap width - vertical marginal discrepancy - was measured under a light microscope with a magnification of x100. Measurements were made without cementation. The mean marginal gap widths and standard deviations were calculated and a one-way analysis of variance (ANOVA) was performed for different types of preparations in order to detect differences (α = 0.05). RESULTS: The mean marginal gap was 30 ± 3 µm for the C group and 28 ± 4 µm for the RS group. The one-way ANOVA showed no statistical significant difference between the two groups (P = 0.23). CONCLUSIONS: Within the limitations of this study, the marginal discrepancies were all within the clinical acceptable standard set at 120 µm. Chamfer and shoulder preparations did not show differences regarding the gap dimension. CLINICAL SIGNIFICANCE: Bur design is an easily selected parameter before natural tooth preparation. Both tested finish lines are able to help clinicians in obtaining acceptable marginal fit values for the investigated zirconia copings.

Degree of conversion of dual-cure resins light-cured through glass-fiber posts.

PURPOSE: To evaluate the degree of conversion (DC) of dual-curing materials used to lute glass-fiber posts in a simulated root canal polymerized by two different modalities. METHODS: Artificial root canals were used to simulate a clinical condition to lute 45 posts by three different dual curing luting cements (Calibra, Multilink Automix and Variolink II). Two light cure modalities were chosen for each luting cement: standard (S group) 400 mW/cm2 for 120 seconds and high-power (H group) 1200 mW/cm2 for 40 seconds. Raman spectra were collected at different positions in the post surface (1, 3, 5 and 7 mm from the coronal-most portion of the post covered in cement) and the percentage degree of conversion was computed. The data were analyzed using ANOVA and post-hoc Student-Neuman-Keuls t-test (P = 0.05). RESULTS: The DC of the tested luting composites decreased progressively while increasing the distance from the light tip. Regardless of the polymerization modality (H or S) applied. Conversely, the curing modality significantly influenced the DC of the tested materials, evidencing different responses to the same energy density: Calibra seemed to be less dependent on light-curing than the other tested materials, showing a constant behavior. Multilink Automix reached the highest DCs in the S group compared to the H mode. Variolink II showed an interesting drawback in DC at 7 mm when cured in the H model. Dual-cure materials show adequate monomer conversion but when the distance from the curing light increased, a variable, but significant lowering in conversion rate was observed. In addition, the time and power of curing appeared to be material-dependent and should be calibrated individually.

Degree of conversion of three composite materials employed in the adhesive cementation of indirect restorations: a micro-Raman analysis.

OBJECTIVES: Adhesive luting of indirect restorations can be carried out employing dual- or light-curing materials. This in vitro study evaluated the degree of conversion (DC) of the materials employed in this procedure, seeking how the combination of time and power of curing applied during polymerisation, as well as the temperature of the light-curing composite, influenced the DC. MATERIALS AND METHODS: One hundred and eighty onlays of different thicknesses (2 mm, 3 mm, 4 mm) were luted with three different composites: two dual-curing cements (Variolink II and Calibra) and a light-curing composite (Venus). The same halogen lamp was used with three different modalities selected to provide a constant quantity of energy. The time/power combinations tested were 400 mW/cm(2) for 120 s, 800 mW/cm(2) for 60s and 1200 mW/cm(2) for 40 s. The light-curing composite was employed at room temperature and after preheating at 54 degrees C. Each sample was examined in three positions using the Micro-Raman Dilor HR LabRam spectrometer to evaluate the polymer conversion degree. The data were analysed using analysis of variance and the Student-Newman-Keuls test (p=0.05). RESULTS: The dual-curing materials showed average conversion percentages close to 64%, although onlays thickness clearly influence the degree of conversion, the light-curing composite showed satisfactory results only when onlays thickness was thin, however preheating significantly improved the performance of the light-curing composite under onlays of great thickness. CONCLUSIONS: Optimal luting of indirect restorations is clearly dependent from light source power, irradiation time and dual-cure luting cement or light-curing composite chosen. It should be calibrated for each material to acquire high DCs. Preheating of light-curing only composites allows for the materials to reach optimal conversion degrees.